Backlight Module and Input Device

1. A backlight module, disposed under a plurality of key caps, comprising: a reflector; a light guide plate, disposed on the reflector, the light guide plate having a plurality of diffusing elements; a light source, located on a light incident side of the light guide plate; and a shading plate, disposed on the light guide plate, wherein the shading plate has a shading area and a translucent area, the plurality of diffusing elements are arranged corresponding to the translucent area, a transmittance of the translucent area is greater than a transmittance of the shading area, and a plurality of scattering or diffusion particles are arranged in the translucent area, wherein the shading plate comprises a transparent sheet, and an opaque layer and a translucent coating respectively disposed on the transparent sheet, the shading area corresponds to a portion covered by the opaque layer, the translucent area corresponds to a portion covered by the translucent coating but not covered by the opaque layer.

2. The backlight module of claim 1 , wherein the translucent coating is white or whitish or light-colored.

3. The backlight module of claim 1 , wherein the plurality of diffusing elements comprise at least one concave-convex microstructure or at least one dent, disposed on a bottom surface or a top surface of the light guide plate corresponding to the plurality of key caps.

4. The backlight module of claim 1 , wherein the shading plate has at least one opening located below a gap between two of the adjacent key caps or disposed at a boundary between the shading area and the translucent area.

5. The backlight module of claim 1 , wherein the transmittance of the translucent area is between 50% and 70%.

6. An input device, comprising: a bracket, having at least one opening; a circuit film, disposed on the bracket; a key cap, disposed on the circuit film; a connecting component, disposed between the key cap and the bracket; and a backlight module, disposed under the bracket, and comprising: a reflector; a light guide plate, disposed on the reflector, and comprising a plurality of diffusing elements; a light source, located on a light incident side of the light guide plate; and a shading plate, disposed on the light guide plate, the shading plate having a shading area, a transparent area, and a translucent area, wherein a coverage of the translucent area at least overlaps a portion of the plurality of diffusing elements, a transmittance of the transparent area is greater than a transmittance of the translucent area, the transmittance of the translucent area is greater than a transmittance of the shading area, and the translucent area has the transmittance of less than 80%.

7. The input device of claim 6 , wherein the shading plate comprises a translucent sheet and an opaque layer coated on the translucent sheet, the translucent sheet has a transmittance of between 50% and 70%, the transmittance of the translucent sheet is greater than a transmittance of the opaque layer, the shading area is a portion covered by the opaque layer, and the translucent sheet is a flexible polymer film containing a plurality of scattering or diffusion particles.

8. The input device of claim 6 , wherein the shading plate comprises a transparent sheet, and an opaque layer and a translucent coating respectively coated on the transparent sheet, the shading area is a portion covered by the opaque layer, and the translucent area is a portion covered by the translucent coating but not covered by the opaque layer, wherein the transmittance of the translucent area is less than a transmittance of the transparent sheet.

9. The input device of claim 6 , wherein the key cap has a light transmitting portion, corresponding to a portion of the plurality of diffusing elements, the translucent area of the shading plate, the opening of the bracket and the light transmitting portion of the key cap.

10. The input device of claim 6 , wherein the plurality of diffusing elements comprise concave-convex microstructures or dents, disposed on a bottom surface or a top surface of the light guide plate corresponding to the key cap.

11. The input device of claim 6 , wherein one of the plurality of diffusing elements comprises a first microstructure and a second microstructure integrally connected to each other, the first microstructure is located on a periphery of the second microstructure, and a first thickness of the light guide plate at the first microstructure is different from a second thickness of the light guide plate at the second microstructure.

12. The input device of claim 6 , wherein the translucent area has a white or whitish color, and the key cap comprises a light-colored coating.

13. An input device, comprising: a bracket; a circuit film, disposed on the bracket; a key cap, disposed on the circuit film; and a backlight module, being disposed underneath the bracket, and comprising: a light guide plate, comprising a plurality of diffusing elements; a shading plate, disposed on the light guide plate, wherein the shading plate comprises a shading area, a transparent area, and a translucent area, wherein a transmittance of the transparent area is greater than a transmittance of the translucent area, and the transmittance of the translucent area is greater than a transmittance of the shading area; and a light source, adjacent to the light guide plate, wherein the shading area surrounds the transparent area, and the translucent area of the shading plate is arranged at a position corresponding to a light transmitting portion of the key cap.

14. The input device of claim 13 , wherein the translucent area is semi-transparent or whitish.

15. The input device of claim 13 , wherein a coverage of the translucent area overlaps at least one of the diffusing elements at a position corresponding to an opening of the bracket.